pregnant? light discharge HELP!!

i am a very worried and concerned 19 year old and i think i may be pregnant but i am really not sure at all. i ALWAYS make sure my boyfriend uses a condom, everytime we have sex. i believe the last time we had sex was either on november 30, 2007 or december 1, 2007. my last period was from december 12th and lasted through the 19th. on december 24th i woke up with some small light pinkish/brownish discharge. this lasted until about december 26th. i was worried that this could be implantation bleeding. but i also am not sure because it came 4-5 days after i was done with my period. i thought implantation bleeding occurred 6-10 days after ovulation. lately i have also been getting a lot of headaches and just feel the need to urinate. i just feel pressure on my bladder. before we have sex, i always make my boyfriend orgasm first and then he urinates before intercourse. i am worried because i think i may have released two eggs instead of one, and perhaps one egg got fertilized and the other didn't (that one being my period). what are the chances of that scenario happening? if i get my period, it should come on january 8th. my cycle is 28 days. is there anyone that could give me some advice!! i'm REALLY worried about this and it is seriously stressing me out! any help will be very much appreciated!!!